Resin-made fuel tank

ABSTRACT

A resin-made fuel tank includes: a resin-made fuel tank body provided by bonding an upper half body and a lower half body to each other; and a barrier sheet layer provided on an inner surface of the fuel tank body and provided for reducing permeation of fuel from the fuel tank body, wherein an edge of the barrier sheet layer is disposed in a vicinity of an upper bonding surface and a lower bonding surface where the upper half body and the lower half body are bonded to each other in a mating manner, the edge has a bent portion which bends toward an outside of the fuel tank body, and the bent portion is embedded in the fuel tank body at a position spaced apart from the upper bonding surface and the lower bonding surface.

INCORPORATION BY REFERENCE

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2017-188800 filed on Sep. 28, 2017. Thecontent of the application is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present invention relates to a resin-made fuel tank.

BACKGROUND ART

Conventionally, there has been known a resin-made fuel tank whichincludes: a resin-made fuel tank body provided by bonding split bodiesto each other; and a barrier sheet layer provided on an inner surface ofthe fuel tank body and provided for reducing permeation of fuel from thefuel tank body (see Patent Literature 1, for example). In PatentLiterature 1, on a bonding surface where the split bodies are bonded toeach other, the barrier sheet layers provided on the respective splitbodies are bonded to each other in a butting manner, and the fuel tankbody is bonded at a position outside the bonding portions of the barriersheet layers.

CITATION LIST Patent Literature

[Patent Literature 1] JP-A No. H10-157738

SUMMARY OF INVENTION Technical Problem

However, in the above-mentioned conventional resin-made fuel tank, onthe bonding surface, in addition to the fuel tank body, the barriersheet layers are bonded to each other and hence, the manufacture of theresin-made fuel tank becomes difficult.

The present invention has been made in view of the above-mentionedcircumstances, and it is an object of the present invention to providetechnique for easily manufacturing a resin-made fuel tank which includesa barrier sheet layer.

Solution to Problem

The present invention is directed to a resin-made fuel tank whichincludes: a resin-made fuel tank body (35) provided by bonding splitbodies (45, 46) to each other; and a barrier sheet layer (36) providedon an inner surface of the fuel tank body (35) and provided for reducingpermeation of fuel from the fuel tank body (35). In the resin-made fueltank body (35), an edge of the barrier sheet layer (36) is disposed in avicinity of bonding surfaces (47 c, 48 c) where the split bodies (45,46) are bonded to each other in a mating manner, the edge has a bentportion (61, 62) which bends toward an outside of the fuel tank body(35), and the bent portion (61, 62) is embedded in the fuel tank body(35) at a position spaced apart from the bonding surface (47 c, 48 c).

In the present invention, the bent portion (61, 62) may extend towardthe outside of the fuel tank body (35) parallel to the bonding surface(47 c, 48 c).

In the present invention, a width (W1, W2) of a bonding portion (47, 48)which has the bonding surface (47 c, 48 c) at an end surface may belarger than a thickness (t1, t2) of a wall portion (45 a, 46 a) of thefuel tank body (35).

In the present invention, the bonding portion (47, 48) may be formed ina flange shape protruding toward the outside of the fuel tank body (35),the bonding portion (47, 48) may have a pressing surface (47 d, 48 d) tobe pressed in applying pressure-bonding to the bonding surface (47 c, 48c), and at least a part of the pressing surface (47 d, 48 d) may overlapwith the bonding surface (47 c, 48 c) in a pressing direction (P).

In the present invention, the split bodies (45, 46) may include onesplit body (45) and the other split body (46), the barrier sheet layer(36) may include one barrier sheet layer (36 a) provided on the onesplit body (45) and the other barrier sheet layer (36 b) provided on theother split body (46), and the bent portion (61) of the one barriersheet layer (36 a) and the bent portion (62) of the other barrier sheetlayer (36 b) may be embedded in the fuel tank body (35) in aspaced-apart manner from each other.

In the present invention, the barrier sheet layer (36) may be formed byadhering a high density polyethylene layer (57 a, 57 b) to both surfacesof an ethylene vinyl alcohol copolymer layer (55) with an adhesive layer(56) interposed therebetween, and the barrier sheet layer (36) may bebonded to the inner surface of the fuel tank body (35) made of highdensity polyethylene with a high density polyethylene layer (57 a)interposed therebetween.

In the present invention, a cut surface (61 a, 62 a) trimmed in athickness direction may be formed on a distal end of the bent portions(61, 62) by a cutting blade.

In the present invention, the bonding surface (47 c, 48 c) may include:a planar surface portion (47 a, 48 a) disposed perpendicular to apressure bonding direction of the bonding surface portion (47 c, 48 c);and an inclined surface portion (47 b, 48 b) inclined with respect tothe planar surface portion (47 a, 48 a), the bonding portion (47, 48)having the bonding surface (47 c, 48 c) on an end surface may be formedin a flange shape protruding toward the outside of the fuel tank body(35), the bonding portion (47, 48) may include a pressing surface (47 d,48 d) to be pressed in applying pressure-bonding to the bonding surface(47 c, 48 c), and a width of the bonding portion (47, 48) may be smallerat the inclined surface portion (47 b, 48 b) than at the planar surfaceportion (47 a, 48 a).

Advantageous Effects of Invention

According to a resin-made fuel tank of the present invention, theresin-made fuel tank includes: a resin-made fuel tank body provided bybonding split bodies to each other; and a barrier sheet layer providedon an inner surface of the fuel tank body and provided for reducingpermeation of fuel from the fuel tank body, wherein an edge of thebarrier sheet layer is disposed in a vicinity of bonding surfaces wherethe split bodies are bonded to each other in a mating manner, the edgehas a bent portion which bends toward an outside of the fuel tank body,and the bent portion is embedded in the fuel tank body at a positionspaced apart from the bonding surface.

With such a configuration, at the edge of the barrier sheet layer, thebent portion of the edge which bends toward an outside of the fuel tankbody is embedded in the fuel tank body and hence, the barrier sheetlayer is firmly joined to the fuel tank body and is minimally influencedwhen the bonding surfaces of the split bodies are bonded to each other.Further, the bent portion is spaced apart from the bonding surface ofthe split body and hence, the bent portion is not bonded at the bondingsurface. Accordingly, at the time of bonding the bonding surface, it isunnecessary to control the bonding of the barrier sheet layer and hence,the resin-made fuel tank can be easily manufactured.

In the above-mentioned present invention, the bent portion may extendtoward the outside of the fuel tank body parallel to the bondingsurface. With such a configuration, the bent portion is disposedperpendicular to the bonding direction of the bonding surface and hence,the bent portion can efficiently receive a force generated at the timeof bonding the split bodies.

In the above-mentioned present invention, a width of a bonding portionwhich has the bonding surface at an end surface may be larger than athickness of a wall portion of the fuel tank body. With such aconfiguration, the bonding surface can ensure a large area and hence, abonding strength of the bonding surface can be increased.

In the above-mentioned present invention, the bonding portion may beformed in a flange shape protruding toward the outside of the fuel tankbody, the bonding portion may have a pressing surface to be pressed inapplying pressure-bonding to the bonding surface, and at least a part ofthe pressing surface may overlap with the bonding surface in a pressingdirection. With such a configuration, at a portion where the pressingsurface overlaps with the bonding surface in a pressing direction, apressing force of the pressing surface can be directly transmitted tothe bonding surface. Accordingly, the split bodies can be stronglybonded to each other.

In the above-mentioned present invention, the split bodies may includeone split body and other split body, the barrier sheet layer may includeone barrier sheet layer provided on the one split body and the otherbarrier sheet layer provided on the other split body, and the bentportion of the one barrier sheet layer and the bent portion of the otherbarrier sheet layer may be embedded in the fuel tank body in aspaced-apart manner from each other. With such a configuration, the bentportion of one barrier sheet layer and the bent portion of the otherbarrier sheet layer are embedded in the fuel tank body in a spaced apartmanner from each other and hence, the bent portions are not bonded toeach other at the bonding surface. Accordingly, at the time of bondingthe bonding surface, it is unnecessary to control the bonding of thebarrier sheet layer and hence, the resin-made fuel tank can be easilymanufactured.

In the above-mentioned present invention, the barrier sheet layer may beformed by adhering a high density polyethylene layer to both surfaces ofan ethylene vinyl alcohol copolymer layer with an adhesive layerinterposed therebetween, and the barrier sheet layer may be bonded tothe inner surface of the fuel tank body made of high densitypolyethylene with a high density polyethylene layer interposedtherebetween. With such a configuration, the high density polyethylenelayer of the barrier sheet layer is bonded to the inner surface of thefuel tank body made of high density polyethylene which is made of thesame material as the high density polyethylene layer of the barriersheet layer. Accordingly, the barrier sheet layer can be strongly bondedto the inner surface of the fuel tank body.

In the above-mentioned present invention, a cut surface trimmed in athickness direction may be formed on a distal end of the bent portionsby a cutting blade. With such a configuration, dimensional accuracy ofthe bent portion can be enhanced and hence, the bent portion can beproperly embedded in the fuel tank body.

In the above-mentioned present invention, the bonding surface mayinclude: a planar surface portion disposed perpendicular to a pressurebonding direction of the bonding surface; and an inclined surfaceportion inclined with respect to the planar surface portion, the bondingportion having the bonding surface on an end surface may be formed in aflange shape protruding toward the outside of the fuel tank body, thebonding portion may include a pressing surface to be pressed in applyingpressure-bonding to the bonding surface, and a width of the bondingportion may be smaller at the inclined surface portion than at theplanar surface portion. With such a configuration, although the inclinedsurface portion has a small compression bonding force compared to theplanar surface portion perpendicular to a compression bonding directionat the time of compression bonding, the width of the inclined surfaceportion is smaller than the width of the planar surface portion andhence, a surface pressure of the inclined surface portion becomessufficiently large. Accordingly, it is possible to favorably bond boththe planar surface portion and the inclined surface portion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a front portion of a motorcycleaccording to a first embodiment of the present invention as viewed froma left rear side.

FIG. 2 is a perspective view of a fuel tank as viewed from a left upperside.

FIG. 3 is a cross-sectional view of the fuel tank by cutting the fueltank at the center of the fuel tank in a vehicle width direction.

FIG. 4 is a left side view showing a state where the fuel tank is splitin two.

FIG. 5 is a schematic view showing manufacturing steps of a fuel tankbody.

FIG. 6 is a cross-sectional view showing the configuration of the fueltank in a plate thickness direction.

FIG. 7 is a cross-sectional view of a portion where an upper half bodyand a lower half body are bonded to each other at a planar portion.

FIG. 8 is a cross-sectional view showing a state before the upper halfbody and the lower half body are bonded to each other in FIG. 7.

FIG. 9 is a perspective view of a front mounting stay as viewed from aleft upper side.

FIG. 10 is a cross-sectional view taken along a line X-X in FIG. 9

FIG. 11 is a perspective view of a rear mounting stay as viewed from aleft rear side.

FIG. 12 is a cross-sectional view taken along a line XII-XII in FIG. 11.

FIG. 13 is a cross-sectional view taken along a line XIII-XIII in FIG.2.

FIG. 14 is a cross-sectional view for explaining machining applied to amouthpiece mounting cylinder portion.

FIG. 15 is a view of an inner protruding portion of a mouthpiece fixingportion and a portion around the inner protruding portion as viewed fromthe inside of the fuel tank body.

FIG. 16 is a cross-sectional view showing a mounting state of amouthpiece having an error in size in the mouthpiece mounting cylinderportion.

FIG. 17 is a perspective view of a mounting structure of a fuel tankaccording to a second embodiment as viewed from a left upper side.

FIG. 18 is a schematic view of the mounting structure of the fuel tankas viewed from a front side.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention are described withreference to drawings. In the description, directions of front and rear,left and right, and up and down are equal to directions of a vehiclebody unless otherwise specified. In the respective drawings, symbol FRindicates a front side of the vehicle body, symbol UP indicates an upperside of the vehicle body, and symbol LH indicates a left side of thevehicle body.

FIG. 1 is a perspective view of a front portion of a motorcycleaccording to a first embodiment of the present invention as viewed froma left rear side.

A motorcycle 1 is a vehicle where an engine 10 which forms a power unitis supported on a vehicle body frame F, a steering system 11 whichsupports a front wheel 2 in a steerable manner is supported on a frontend of the vehicle body frame F in a steerable manner, and a swing arm(not shown in the drawing) which supports a rear wheel (not shown in thedrawing) is provided on a rear portion side of the vehicle body frame F.The motorcycle 1 is a saddle riding vehicle where a seat 13 on which arider seats in a straddling manner is disposed above a rear portion ofthe vehicle body frame F.

The vehicle body frame F includes a head pipe portion 14, a pair of leftand right main frames 15, 15, a down frame 16, a pair of left and rightpivot frames (not shown in the drawing), a pair of left and right seatframes 17, 17 (the left seat frame not shown in the drawing), and a pairof left and right sub frames (not shown in the drawing).

The head pipe portion 14 is provided on a front end of the vehicle bodyframe F.

The main frames 15, 15 extend rearward in a rearward and downwarddirection from the head pipe portion 14.

The down frame 16 extends downward from the head pipe portion 14 at aposition below the main frames 15, 15, and extends rearward after beingbent behind the front wheel 2.

The above-mentioned pivot frames extend downward from rear end portionsof the main frames 15, 15, and are connected to a rear end of the downframe 16.

The seat frames 17, 17 extend rearward from rear end portions of themain frames 15, 15.

The above-mentioned sub frames extend rearward and upward from the pivotframes, and are connected to rear ends of the seat frames 17, 17.

The steering system 11 includes a steering shaft 20 which is pivotallysupported on the head pipe portion 14, a top bridge 21 which is fixed toan upper end of the steering shaft 20, a bottom bridge 22 which is fixedto a lower end of the steering shaft 20, a pair of left and right frontforks 23, 23 which is supported on the top bridge 21 and the bottombridge 22, and a steering handle 24 which is fixed to the top bridge 21.

The front wheel 2 is pivotally supported on lower end portions of thefront forks 23, 23. A front fender 25 is supported on the bottom bridge22.

The engine 10 is positioned below the main frames 15, 15, and isdisposed between the down frame 16 and the above-mentioned pivot framesin the longitudinal direction of the vehicle.

The seat 13 is disposed above the seat frames 17, 17, and is supportedon the seat frames 17, 17.

The fuel tank 30 (resin-made tank) is disposed above the main frames 15,15 along the main frames 15, 15, and is supported on the main frames 15,15. The fuel tank 30 is disposed between the head pipe portion 14 andthe seat 13 in the longitudinal direction of the vehicle. A front endportion of the seat 13 covers an upper surface of a rear portion of thefuel tank 30 from above.

FIG. 2 is a perspective view of the fuel tank 30 as viewed from a leftupper side.

As shown in FIG. 1 and FIG. 2, a filler opening 31 is provided on anupper surface of a front portion of the fuel tank 30. A tank cap 32 ismounted on the filler opening 31, and the filler opening 31 is closed bythe tank cap 32.

A tray 33 which surrounds the filler opening 31 from the periphery ofthe filler opening 31 is mounted on the fuel tank 30. The tray 33 isdisposed between a lower end of the tank cap 32 and the upper surface ofthe fuel tank 30.

A drain pipe 33 a extending downward is provided on the tray 33. Fuelleaked at the time of filling fuel or the like is received by the tray33, and is discharged downward through the drain pipe 33 a.

FIG. 3 is a cross-sectional view of the fuel tank 30 obtained by cuttingthe fuel tank 30 at the center of the fuel tank 30 in the vehicle widthdirection. FIG. 4 is a left side view showing a state where the fueltank 30 is split in two.

With reference to FIG. 2 to FIG. 4, the fuel tank 30 includes aresin-made fuel tank body 35 (tank body), and a barrier sheet layer 36which is provided on approximately the whole inner surface of the fueltank body 35.

The barrier sheet layer 36 is made of a material having lower fuelpermeability than a material for forming the fuel tank body 35. Due tothe provision of the barrier sheet layer 36, it is possible to preventleakage of fuel such as gasoline stored in the fuel tank 30 to theoutside through the fuel tank 30.

A front mounting stay 37 (mounting stay) which projects frontward isprovided on an upper portion of a front portion of the fuel tank body35.

The front portion of the fuel tank body 35 is fixed to an upper surfaceof a rear portion of the head pipe portion 14 by a tank fixing jig 39 a(fixing jig, see FIG. 1) which passes through the front mounting stay 37from above.

A pair of left and right rear mounting stays 38L, 38R (mounting stays)which projects downward is provided on a lower portion of a rear portionof the fuel tank body 35.

The main frames 15, 15 include tank stays 15 a, 15 a (FIG. 1) whichextend upward on rear portions thereof respectively.

A rear portion of the fuel tank body 35 is fixed to the tank stays 15 a,15 a by tank fixing jigs 39 b, 39 b (fixing jigs, see FIG. 1) which passthrough the rear mounting stays 38L, 38R respectively from the outsidein the vehicle width direction.

The fuel tank body 35 includes a cylindrical filling portion 40 forfilling fuel (for filling liquid) on the upper portion of the frontportion thereof. The cylindrical filling portion 40 is a cylinderextending in the vertical direction, and an upper end portion of thecylindrical filling portion 40 forms the filler opening 31.

The cylindrical filling portion 40 is made of the same resin material asa resin material for forming the fuel tank body 35, and is formedintegrally with the fuel tank body 35.

As shown in FIG. 2, a metal-made mouthpiece 41 (not shown in thedrawings in FIG. 3 and FIG. 4) is mounted on the cylindrical fillingportion 40. The mouthpiece 41 is fixed to the upper surface of the fueltank body 35 by a plurality of mouthpiece fixing jigs 42 (fixing jigs)which are made to pass through the mouthpiece 41 from above.

The fuel tank body 35 includes a pump mounting opening portion 44 onwhich the fuel pump 43 is mounted on a lower surface of the fuel tankbody 35.

The fuel tank body 35 has the two-split structure where the fuel tankbody 35 is split into an upper half body 45 (split body, one split body)which forms an upper portion of the fuel tank body 35, and a lower halfbody 46 (split body, the other split body) which forms a lower portionof the fuel tank body 35. The fuel tank body 35 is formed into a tankshape by bonding the upper half body 45 and the lower half body 46 toeach other.

The upper half body 45 is formed into a case shape having a lowersurface thereof opened downward. A peripheral portion of an opening on alower surface of the upper half body 45 forms an upper bonding portion47 (bonding portion) to be bonded to the lower half body 46. As viewedin a side view of a vehicle, the upper bonding portion 47 has a planarsurface portion 47 a extending approximately horizontally on a rearportion of the upper bonding portion 47, and an inclined surface portion47 b which extends frontward in an inclined manner in a frontward andupward direction with respect to the planar surface portion 47 a.

The front mounting stay 37 is provided on a front end portion of theupper half body 45. The cylindrical filling portion 40 is provided on anupper surface of a front portion of the upper half body 45.

The lower half body 46 is formed into a case shape having an uppersurface thereof opened upward. A peripheral portion of an opening on anupper surface of the lower half body 46 forms a lower bonding portion 48(bonding portion) to be bonded to the upper half body 45. As viewed in aside view of the vehicle, the lower bonding portion 48 has a planarsurface portion 48 a which is parallel to the planar surface portion 47a, and an inclined surface portion 48 b which is parallel to theinclined surface portion 47 b. The planar surface portion 47 a is bondedto the planar surface portion 48 a, and the inclined surface portion 47b is bonded to the inclined surface portion 48 b.

The rear mounting stays 38L, 38R are provided on a rear portion of thelower half body 46. The pump mounting opening portion 44 is provided ona lower surface of the lower half body 46.

To be more specific, the upper half body 45 and the lower half body 46are formed into an integral body by being welded to each other at aportion where an upper bonding surface 47 c (bonding surface) which isformed of a lower surface of the upper bonding portion 47 of the upperhalf body 45 and a lower bonding surface 48 c (bonding surface) which isformed of an upper surface of the lower bonding portion 48 of the lowerhalf body 46 are mated to each other.

The barrier sheet layer 36 includes: an upper barrier sheet layer 36 a(one barrier sheet layer) which is bonded to an inner surface of theupper half body 45; and a lower barrier sheet layer 36 b (the otherbarrier sheet layer) which is bonded to an inner surface of the lowerhalf body 46.

FIG. 5 is a schematic view showing manufacturing steps of the fuel tankbody 35.

With reference to FIG. 5, a plurality of materials for forming thebarrier sheet layer 36 are supplied to a press-molding die 51, and asheet-like molded body 50 is extruded from the die 51.

The molded body 50 is formed into a shape which conforms to an innersurface of the fuel tank body 35 by a vacuum molding machine 52. Aperipheral portion of the formed barrier sheet layer 36 is trimmed by atrimming die (not shown in the drawing).

The trimmed barrier sheet layer 36 is set in the inside of a die 53 forinjection molding provided for forming the fuel tank body 35, and thebarrier sheet layer 36 is integrally formed with the fuel tank body 35at the time of forming the fuel tank body 35 by injection molding. Thatis, the barrier sheet layer 36 is bonded to the inner surface of thefuel tank body 35 by insert molding.

The upper barrier sheet layer 36 a and the lower barrier sheet layer 36b are molded separately.

The upper barrier sheet layer 36 a is bonded to the upper half body 45at the time forming the upper half body 45 by injection molding, and thelower barrier sheet layer 36 b is bonded to the lower half body 46 atthe time of forming the lower half body 46 by injection molding.

Then, the upper bonding surface 47 c and the lower bonding surface 48 care welded by heating, and the upper bonding surface 47 c and the lowerbonding surface 48 c are adhered to each other by pressure bonding andhence, the upper half body 45 and the lower half body 46 are integrallyformed with each other.

FIG. 6 is a cross-sectional view showing the configuration of the fueltank 30 in a plate thickness direction.

The fuel tank 30 is formed of six layers in total. That is, the fueltank body 35 is formed of one layer, and the barrier sheet layer 36 isformed of five layers.

The barrier sheet layer 36 includes a barrier layer 55, adhesive layers56, 56 provided on both surfaces of the barrier layer 55, and outerlayers 57 a, 57 b adhered to both sides of the barrier layer 55 with theadhesive layers 56, 56 interposed therebetween.

As one example of a material for forming the fuel tank body 35,high-density polyethylene (HDPE) can be named.

The barrier layer 55 is made of a material which minimally allowspermeation of fuel compared to high density polyethylene. As oneexample, the barrier layer 55 is made of ethylene vinyl alcoholcopolymer (EVOH).

The outer layers 57 a, 57 a are made of the same material as the fueltank body 35, and are made of high density polyethylene as one example.

The barrier sheet layer 36 is bonded to the inner surface of the fueltank body 35 with the outer layer 57 on a fuel tank body 35 sideinterposed therebetween. The barrier sheet layer 36 is bonded to theinner surface of the fuel tank body 35 with the outer layer 57 a made ofthe same material as the fuel tank body 35 interposed therebetween andhence, the barrier sheet layer 36 is strongly bonded to the fuel tankbody 35 with high adhesiveness to the fuel tank body 35.

With respect to the barrier sheet layer 36, the outer layer 57 b isexposed to the inside of the fuel tank body 35 and is brought intocontact with fuel. Accordingly, it is possible to prevent direct contactof fuel with the barrier layer 55.

FIG. 7 is a cross-sectional view of the portion where the upper halfbody 45 and the lower half body 46 are bonded to each other at theplanar surface portions 47 a, 48 a.

The upper bonding portion 47 is formed in a flange shape protruding froman outer surface of the upper half body 45 toward the outside of thefuel tank body 35. The upper bonding portion 47 is provided over thewhole circumference of the upper half body 45.

A width W1 of the upper bonding portion 47 is larger than a thickness t1of a side wall portion 45 a (wall portion) of the upper half body 45.

A pressing surface 47 d which is disposed parallel to the upper bondingsurface 47 c is formed on an upper surface of a distal end portion ofthe flange-shaped upper bonding portion 47.

The upper half body 45 includes a peripheral rib 47 e extending upwardfrom an upper portion of the distal end surface of the upper bondingportion 47. The peripheral rib 47 e is provided over the substantiallywhole circumference of the upper half body 45.

The pressing surface 47 d is a bottom surface of a groove portion 58which is formed between the peripheral rib 47 e and the outer surface ofthe upper half body 45.

The upper half body 45 is pressed to the lower bonding surface 48 c ofthe lower half body 46 by a pressing jig J1 which is engaged with thegroove portion 58 and presses the pressing surface 47 d.

The pressing surface 47 d overlaps with the upper bonding surface 47 cin a pressing direction P of the pressing jig J1. Accordingly, it ispossible to directly press the upper bonding surface 47 c by thepressing jig J1 thus favorably performing pressure bonding.

The lower bonding portion 48 is formed in a flange shape protruding froman outer surface of the lower half body 46 toward the outside of thefuel tank body 35. The lower bonding portion 48 is provided over thewhole circumference of the lower half body 46.

A width W2 of the lower bonding portion 48 is larger than a thickness t2of a side wall portion 46 a (wall portion) of the lower half body 46.

A pressing surface 48 d which is disposed parallel to the lower bondingsurface 48 c is formed on a lower surface of a distal end portion of theflange-shaped lower bonding portion 48.

The lower half body 46 includes a peripheral rib 48 e which extendsdownward from a lower portion of the distal end surface of the lowerbonding portion 48. The peripheral rib 48 e is provided over thesubstantially whole circumference of the lower half body 46.

The pressing surface 48 d is a bottom surface of a groove portion 59which is formed between the peripheral rib 48 e and the outer surface ofthe lower half body 46.

The lower half body 46 is pressed to the upper bonding surface 47 c ofthe upper half body 45 by a pressing jig J2 which is engaged with thegroove portion 59 and presses the pressing surface 48 d.

The pressing surface 48 d overlaps with the lower bonding surface 48 cin a pressing direction P of the pressing jig J2. Accordingly, it ispossible to directly press the lower bonding surface 48 c by thepressing jig J2 thus favorably performing pressure bonding.

The pressing direction P is a direction along which the upper half body45 and the lower half body 46 are bonded to each other.

An edge of the upper barrier sheet layer 36 a is disposed in thevicinity of the upper bonding surface 47 c, and a bent portion 61 whichbends toward the outside of the fuel tank body 35 is formed on the edge.

The bent portion 61 bends at an approximately right angle with respectto a body portion 36 a 1 of the upper barrier sheet layer 36 a disposedalong the inner surface of the upper half body 45.

To be more specific, the bent portion 61 is embedded in the innersurface of the upper half body 45 at a position away from the upperbonding surface 47 c upwardly by a distance D. The bent portion 61extends to the outside of the fuel tank body 35 so as to be parallel tothe upper bonding surface 47 c.

The bent portion 61 is disposed between the pressing surface 47 d andthe upper bonding surface 47 c in the pressing direction P. A length ofthe bent portion 61 is smaller than the thickness t1 of the side wallportion 45 a.

An edge of the lower barrier sheet layer 36 b is disposed in thevicinity of the lower bonding surface 48 c, and a bent portion 62 whichbends toward the outside of the fuel tank body 35 is formed on the edge.

The bent portion 62 bends at an approximately right angle with respectto a body portion 36 b 1 of the lower barrier sheet layer 36 b disposedalong the inner surface of the lower half body 46.

To be more specific, the bent portion 62 is embedded in the innersurface of the lower half body 46 at a position away from the lowerbonding surface 48 c upwardly by a distance D. The bent portion 62extends to the outside of the fuel tank body 35 so as to be parallel tothe lower bonding surface 48 c.

The bent portion 62 is disposed between the pressing surface 48 d andthe lower bonding surface 48 c in the pressing direction P. A length ofthe bent portion 62 is smaller than the thickness t2 of the side wallportion 46 a.

The bent portions 61, 62 are formed by trimming bent portions ofperipheral portions of the molded bodies 50 which are formed at the timeof molding by the vacuum molding machine 52 (FIG. 5) using cuttingblades of the trimming-use dies (see paragraph 0023). Cut surfaces 61 a,62 a trimmed in the thickness direction of the bent portions 61, 62 areformed on distal ends of the bent portions 61, 62 by the above-mentionedcutting blades. Accordingly, the bent portions 61, 62 can be easilyformed and, at the same time, the bent portions 61, 62 can be formedwith high accuracy.

The bent portions 61, 62 are embedded in the upper half body 45 and thelower half body 46 respectively at the time of molding the upper halfbody 45 and the lower half body 46 by a die 53 (FIG. 5) for injectionmolding. Accordingly, the bent portions 61, 62 can be easily embedded.

FIG. 8 is a cross-sectional view showing a state before bonding in FIG.7.

As shown in FIG. 8, in a state before bonding, the upper bonding portion47 is formed to have a large thickness in the pressing direction P by anamount corresponding to a pressure bonding margin L1 and a meltingmargin L2.

In the same manner, in a state before bonding, the lower bonding portion48 is formed to have a large thickness in the pressing direction P by anamount corresponding to a pressure bonding margin L1 and a meltingmargin L2.

The melting margins L2 are portions to be melted at the time of heatingthe upper bonding portion 47 and the lower bonding portion 48 to theportions of the pressure bonding margins L1, and do not remain in acompleted product of the fuel tank body 35.

The pressure bonding margins L1 are portions to be pressure bonded atthe time of welding, and portions of the pressure bonding margins L1form protruding portions 63, 63 which protrude from the upper bondingsurface 47 c and the lower bonding surface 48 c respectively by pressure(FIG. 7).

The bent portions 61, 62 of the barrier sheet layer 36 are spaced apartfrom the outer protruding portion 63 in the upward direction and in thedownward direction respectively.

In the first embodiment, the bent portions 61, 62 of the barrier sheetlayer 36 are spaced apart from the upper bonding surface 47 c and thelower bonding surface 48 c in the upward direction and in the downwarddirection respectively, and are not welded to the upper bonding surface47 c and the lower bonding surface 48 c respectively. With such aconfiguration, it is unnecessary to control welding of the upper barriersheet layer 36 a and the lower barrier sheet layer 36 b at the time ofwelding the upper bonding surface 47 c and the lower bonding surface 48c to each other and hence, the upper half body 45 and the lower halfbody 46 can be easily welded to each other.

Further, there is a region where the barrier sheet layer 36 does notexist between the bent portion 61 and the bent portion 62. However, sucha region is small and hence, the permeation of fuel to the outsidethrough the region is permissible.

As shown in FIG. 8, the upper bonding portion 47 and the lower bondingportion 48 respectively have a protruding margin extending from an endof the peripheral rib 47 e, 48 e to a distal end of the melting marginL2 in the pressing direction P. A length of the protruding margin is aprotruding size L3. The protruding size L3 is a length in a directionperpendicular to the upper bonding surface 47 c and the lower bondingsurface 48 c. The protruding size L3 may be a length from the pressingsurface 47 d, 48 d to a distal end of the melting margin L2, forexample.

As shown in FIG. 4, when the upper half body 45 and the lower half body46 are moved in the pressing direction P along with welding, in a statewhere the planar surface portion 47 a of the upper bonding portion 47and the planar surface portion 48 a of the lower bonding portion 48 aredisposed parallel to each other, a size of a gap G between the upperbonding surface 47 c and the lower bonding surface 48 c is uniform atany places. That is, the gap G between the planar surface portion 47 aand the planar surface portion 48 a and the gap G between the inclinedsurface portion 47 b and the inclined surface portion 48 b are equal insize. The gap G is a gap in the pressing direction P. Accordingly, it ispossible to make a pressing force in the pressing direction P uniformlyact on the whole upper bonding portion 47 and the whole lower bondingportion 48.

Further, the protruding size L3 is uniform over the whole circumferenceof the upper bonding portion 47 and over the whole circumference of thelower bonding surface 48 c.

The inclined surface portions 47 b, 48 b are inclined with respect tothe pressing direction P and hence, a pressing force acting on theinclined surface portions 47 b, 48 b at the time of welding becomessmaller than a pressing force acting on the planar surface portions 47a, 48 a.

In this first embodiment, to describe with reference to FIG. 7, thewidth W3 of the upper bonding portion 47 and the lower bonding portion48 (portions indicated by an imaginary line in FIG. 7) at the inclinedsurface portions 47 b, 48 b (FIG. 4) is smaller than the widths W1, W2of the upper bonding portion 47 and the lower bonding portion 48 atplanar surface portions 47 a, 48 a.

With such a configuration, an area of the upper bonding surface 47 c ofthe inclined surface portion 47 b and an area of the lower bondingsurface 48 c of the inclined surface portion 48 b become small, and asurface pressure applied to the inclined surface portions 47 b, 48 b dueto a pressing force in the pressing direction P become large.Accordingly, a pressure surface acting on the whole upper bondingportion 47 and the whole lower bonding portion 48 can be made uniformthus enabling favorable welding.

Next, the structures of the front mounting stay 37 and the rear mountingstays 38L, 38R are described.

FIG. 9 is a perspective view of the front mounting stay 37 as viewedfrom a left upper side. FIG. 10 is a cross-sectional view taken along aline X-X in FIG. 9.

With reference to FIG. 9 and FIG. 10, the front mounting stay 37 isprovided on a center portion of a front end portion of the upper halfbody 45 in a width direction (vehicle width direction) of the fuel tankbody 35, and is positioned in front of the filler opening 31.

The front mounting stay 37 has: a vertical wall portion 70 extendingupward from a front edge of an upper surface of the upper half body 45;a plate-like frontwardly extending portion 71 extending frontward froman upper end of the vertical wall portion 70; and a mounting hole 72which vertically penetrates the frontwardly extending portion 71 in theplate thickness direction.

The vertical wall portion 70 is formed into a plate shape extendingupward along the front edge of the upper surface of the upper half body45. A rear surface of the vertical wall portion 70 is connected to anupper surface of a front end portion of the upper half body 45 by rearsurface ribs 73, 73.

The rear surface ribs 73, 73 are provided in pair on left and right sideedge portions of the rear surface of the vertical wall surface 70. Rearedges of the rear surface ribs 73, 73 extend rearward and downwardtoward the filler opening 31.

The frontwardly extending portion 71 extends frontward in a frontwardand upward direction. A lower surface of the frontwardly extendingportion 71 is connected to a front surface of the vertical wall portion70 by reinforcing ribs 74, 74 (ribs). The reinforcing ribs 74, 74 extenddownward in a left and right pair from left and right side edges of thefrontwardly extending portion 71, and rear ends of the reinforcing ribs74, 74 are connected to left and right side edge portions of a frontsurface of the vertical wall portion 70. Front edges of the reinforcingribs 74, 74 are inclined in a rearward and downward direction as viewedin a side view of the vehicle. Lower end portions 74 a of thereinforcing ribs 74, 74 are connected to an upper portion of theflange-shaped upper bonding portion 47. The reinforcing ribs 74, 74extend from the upper bonding portion 47 to a lower surface of thefrontwardly extending portion 71.

The mounting hole 72 is a circular hole. The mounting hole 72 isdisposed between the left and right reinforcing ribs 74, 74 on thefrontwardly extending portion 71.

A cylindrical collar member 75 having anti-vibration property is fittedin the mounting hole 72, and the tank fixing jig 39 a passes through ahole of the collar member 75 from above. The tank fixing jig 39 a is abolt.

The tank fixing jig 39 a fastens the front mounting stay 37 to thevehicle body frame F (FIG. 1) by way of the collar member 75.

As shown in FIG. 10, the vertical wall portion 70 of the front mountingstay 37 extends upward from the upper surface of the upper half body 45which is spaced apart upward from the upper bonding surface 47 c and thelower bonding surface 48 c. That is, the front mounting stay 37 isintegrally provided to the upper half body 45 at a position away fromthe upper bonding surface 47 c and the lower bonding surface 48 c in thevertical direction.

With such a configuration, an external force which is transmitted to theupper half body 45 by way of the front mounting stay 37 is notconcentrated on the upper bonding surface 47 c and the lower bondingsurface 48 c, and is dispersed to the upper surface portion of the upperhalf body 45. Accordingly, an influence of an external force on thebarrier sheet layer 36 in the vicinity of the upper bonding surface 47 cand the lower bonding surface 48 c can be reduced thus effectivelyprotecting the barrier sheet layer 36.

An upper surface groove 71 a extending in the width direction of thefuel tank body 35 is provided on the upper surface of the frontwardlyextending portion 71 between the mounting hole 72 and the vertical wallportion 70.

A lower surface groove 71 b extending in the longitudinal direction isprovided on a lower surface of the frontwardly extending portion 71between the mounting hole 72 and a front end of the frontwardlyextending portion 71.

At a portion where the upper surface groove 71 a is provided and at aportion where the lower surface groove 71 b is provided, a platethickness of the frontwardly extending portion 71 becomes small, andstrength of the frontwardly extending portion 71 also becomes small.That is, the upper surface groove 71 a and the lower surface groove 71 bare fragile portions which decrease strength of the frontwardlyextending portion 71. Strength of the frontwardly extending portion 71is decreased at the upper surface groove 71 a and the lower surfacegroove 71 b provided around the mounting hole 72.

When an excessive external force acts on the front mounting stay 37, thefront mounting stay 37 is broken first at a portion around the uppersurface groove 71 a or at a portion around the lower surface groove 71 bso that a part of the external force is absorbed by the front mountingstay 37. Accordingly, it is possible to prevent an excessive externalforce from being transmitted to the barrier sheet layer 36 by way of thefront mounting stay 37 thus protecting the barrier sheet layer 36.

FIG. 11 is a perspective view of the rear mounting stay 38L as viewedfrom a left rear side. FIG. 12 is a cross-sectional view taken along aline XII-XII in FIG. 11. The rear mounting stays 38L, 38R are disposedin left and right symmetry and hence, in this embodiment, the rearmounting stay 38L is described in detail, and the description of therear mounting stay 38R is simplified.

With reference to FIG. 11 and FIG. 12, the rear mounting stay 38L ismounted on a left edge portion of a rear portion of the lower half body46. The rear mounting stay 38R is mounted on a right edge portion of arear portion of the lower half body 46.

The rear mounting stay 38L has: a side wall portion 80 extendingdownward from a side edge portion of a lower surface of the lower halfbody 46; and a cylindrical portion 81 integrally provided on a lower endportion of the side wall portion 80.

The side wall portion 80 is formed into a plate shape facing in thevehicle width direction of the motorcycle 1, and is formed into aninverted triangular shape which is tapered downward as viewed in a sideview.

The cylindrical portion 81 is formed into a cylindrical shape protrudingoutward in the vehicle width direction from a lower end portion of theside wall portion 80. The cylindrical portion 81 has a mounting hole 82which penetrates the rear mounting stay 38L in the vehicle widthdirection at the center thereof.

A pair of reinforcing ribs 83, 83 (ribs) which connects an upper portionof the cylindrical portion 81 and a lower surface of the lower half body46 to each other in the vertical direction is provided on an outersurface of the side wall portion 80. The reinforcing ribs 83, 83 aredisposed in pair in a spaced apart manner in the longitudinal direction.

Portions of upper end portions 83 a of the reinforcing ribs 83, 83 areconnected to a lower portion of the flange-shaped lower bonding portion48. The reinforcing ribs 83, 83 extend from the lower bonding portion 48to the cylindrical portion 81.

With reference to FIG. 1 and FIG. 11, a cylindrical collar member 84having anti-vibration property is fitted in the mounting hole 82, andthe tank fixing jig 39 b passes through a hole of the collar member 84from the outside in the vehicle width direction. The tank fixing jig 39b is a bolt.

The tank fixing jig 39 b fastens the rear mounting stay 38L to the tankstays 15 a, 15 a by way of the collar member 84.

As shown in FIG. 12, the side wall portion 80 of the rear mounting stay38L extends downward from a lower surface of the lower half body 46which is downwardly spaced apart from the upper bonding surface 47 c andthe lower bonding surface 48 c. That is, the rear mounting stay 38L isintegrally provided on the lower half body 46 at a position away fromthe upper bonding surface 47 c and the lower bonding surface 48 c in thevertical direction.

With such a configuration, an external force which is transmitted to thelower half body 46 by way of the rear mounting stay 38L is notconcentrated on the upper bonding surface 47 c and the lower bondingsurface 48 c and is dispersed to the lower surface portion of the lowerhalf body 46. Accordingly, an influence of an external force on thebarrier sheet layer 36 in the vicinity of the upper bonding surface 47 cand the lower bonding surface 48 c can be reduced thus effectivelyprotecting the barrier sheet layer 36.

Grooves 83 b, 83 b which are indented toward the inside in the vehiclewidth direction are provided on lower end portions of the reinforcingribs 83, 83 respectively in the vicinity of the outer periphery of thecylindrical portion 81.

At portions where the grooves 83 b, 83 b are provided, plate thicknessesof the reinforcing ribs 83, 83 become small so that strength of the rearmounting stay 38L becomes small. That is, the grooves 83 b, 83 b arefragile portions which decrease strength of the rear mounting stay 38L.The strength of the rear mounting stay 38L becomes small at portionswhere the grooves 83 b, 83 b are provided around the mounting hole 82.

When an excessive external force acts on the rear mounting stay 38L, therear mounting stay 38L is broken first at portions around the grooves 83b, 83 b so that a part of the external force is absorbed by the rearmounting stay 38L. Accordingly, it is possible to prevent an excessiveexternal force from being transmitted to the barrier sheet layer 36 byway of the rear mounting stay 38L thus protecting the barrier sheetlayer 36.

With reference to FIG. 1 to FIG. 3, the front mounting stay 37 and therear mounting stays 38L, 38R are arranged in a spaced apart manner inthe longitudinal direction and in the vertical direction from eachother.

To be more specific, the front mounting stay 37 is provided on the upperportion of the front end portion of the upper half body 45, and the rearmounting stays 38L, 38R are provided on the lower portion of the rearportion of the lower half body 46. That is, the front mounting stay 37and the rear mounting stays 38L, 38R are arranged in a spaced apartmanner in the longitudinal direction and in the vertical direction and,at the same time, are provided on the upper half body 45 and the lowerhalf body 46 in a split manner. With such a configuration, an externalforce acting on the fuel tank body 35 from the front mounting stay 37and the rear mounting stays 38L, 38R can be dispersed in a wide regionof the fuel tank body 35. Accordingly, it is possible to prevent theconcentration of a stress on the barrier sheet layer 36 in the vicinityof the upper bonding surface 47 c and the lower bonding surface 48 cthus effectively protecting the barrier sheet layer 36.

Next, the mounting structure of the mouthpiece 41 is described.

FIG. 13 is a cross-sectional view taken along a line XIII-XIII in FIG.2.

As shown in FIG. 13, the mouthpiece 41 is mounted on the cylindricalfilling portion 40 by engagement. The mouthpiece 41 is fixed to amouthpiece fixing portion 91 (fixing portion) provided on the uppersurface of the fuel tank body 35 by the mouthpiece fixing jig 42. A sealmember 92 is interposed between the mouthpiece 41 and the cylindricalfilling portion 40.

The cylindrical filling portion 40 includes: a mouthpiece mountingcylinder portion 93 which extends upward from the upper surface of theupper half body 45; and a tank inner cylinder portion 94 which extendsto the inside of the fuel tank body 35 as integral parts thereof.

The cylindrical filling portion 40 is integrally formed with the fueltank body 35 at the time of forming the fuel tank body 35 by injectionmolding using the die 53 shown in FIG. 5.

The mouthpiece mounting cylinder portion 93 includes: a proximal endportion 95 which extends upward from the upper surface of the upper halfbody 45; and an upper portion 96 (a portion covered by a fittingportion) which is positioned above the proximal end portion 95. Theproximal end portion 95 and the upper portion 96 are providedconcentrically, and an outer diameter of the proximal end portion 95 isset larger than an outer diameter of the upper portion 96.

An annular seal groove 96 a which is indented radially inwardly isprovided on an outer peripheral portion of the upper portion 96 of themouthpiece mounting cylinder portion 93.

An inner peripheral surface 93 a of the mouthpiece mounting cylinderportion 93 has the same diameter over the whole length of the mouthpiecemounting cylinder portion 93.

A distal end surface 93 b of the mouthpiece mounting cylinder portion 93is flat. A chamfered portion is provided on an inner edge and an outeredge of the distal end surface 93 b.

On the outer peripheral surface 93 c of the mouthpiece mounting cylinderportion 93, a step is formed on an intermediate portion in the verticaldirection due to the difference in outer diameter between the proximalend portion 95 and the upper portion 96.

FIG. 14 is a cross-sectional view for explaining machining applied tothe mouthpiece mounting cylinder portion 93.

In the mouthpiece mounting cylinder portion 93, after forming themouthpiece mounting cylinder portion 93 by injection molding using thedie 53 in FIG. 5, a finished portion 90 shown in FIG. 14 is formed withhigh accuracy by machining. The machining is milling, for example.

To be more specific, the finished portion 90 is formed of: the outerperipheral surface 93 c of the upper portion 96 including the sealgroove 96 a; the distal end surface 93 b; and the inner peripheralsurface 93 a.

The mouthpiece fixing portion 91 includes: an outer protruding portion97 which protrudes upward from the upper surface of the upper half body45; and an inner protruding portion 98 (protruding portion) whichprotrudes toward the inside of the fuel tank body 35. The outerprotruding portion 97 and the inner protruding portion 98 are formed byprotruding a resin which forms the fuel tank body 35.

The mouthpiece fixing portion 91 has a nut 99 embedded in the outerprotruding portion 97 and the inner protruding portion 98.

To be more specific, the mouthpiece fixing portion 91 has a hole portion100 which is indented downward from a flat upper surface of the outerprotruding portion 97, and a nut 99 is embedded in a lower side of thehole portion 100. A threaded portion 99 a of the nut 99 is exposed fromthe hole portion 100 to an upper side. A chamfered portion 99 b isprovided on an outer peripheral portion of a lower end of the nut 99.

Since the mouthpiece fixing portion 91 has the inner protruding portion98, a large embedded length of the nut 99 can be ensured and hence, thenut 99 can be strongly connected to the fuel tank body 35.

The distal end surface 98 a of the inner protruding portion 98 is formedinto a semispherical convex shape, and has a smooth curved shape.

FIG. 15 is a view of the inner protruding portions 98 of the mouthpiecefixing portions 91 and portions around the inner protruding portions 98as viewed from the inside of the fuel tank body 35.

With reference to FIG. 2, FIG. 13 and FIG. 15, a plurality of themouthpiece fixing portions 91 are disposed concentrically around thecylindrical filling portion 40 at a substantially equal interval.

The barrier sheet layer 36 is provided also on the inner protrudingportions 98. The barrier sheet layer 36 provided on the inner protrudingportion 98 forms a curved surface portion 36 c having a smoothly curvedsurface shape along the distal end surface 98 a. Accordingly, it ispossible to prevent concentration of a stress on the barrier sheet layer36 provided on the inner protruding portion 98 and hence, the barriersheet layer 36 can be strongly adhered to the inner surface of the fueltank body 35.

The barrier sheet layer 36 has a folded portion 36 d extending towardthe inside of the fuel tank body 35 around the proximal end portion ofthe tank inner cylinder portion 94. The folded portion 36 d is formedinto an annular shape along an outer peripheral portion of the proximalend portion of the tank inner cylinder portion 94, and is connected tothe outer peripheral portion of the tank inner cylinder portion 94.

The mouthpiece fixing jig 42 includes: a mouthpiece fixing bolt 101(bolt) which is fastened to the nut 99 of the mouthpiece fixing portion91; and a collar 102 through which a threaded portion of the mouthpiecefixing bolt 101 passes.

The collar 102 has: a cylinder portion 102 a fitted in the hole portion100 of the mouthpiece fixing portion 91; and a flange portion 102 bwhich protrudes from the cylinder portion 102 a.

The mouthpiece 41 includes: a cylindrical skirt portion 110 which coversthe outer peripheral surface 93 c of the mouthpiece mounting cylinderportion 93; an inner cylinder portion 111 which is fitted in the innerperipheral surface 93 a of the mouthpiece mounting cylinder portion 93;an end surface portion 112 which connects an upper edge of the skirtportion 110 and a lower edge of the inner cylinder portion 111 to eachother; and a plate-like stay portion 113 which extends from a lower endportion of the skirt portion 110 toward the outside in the radialdirection of the mouthpiece 41.

The skirt portion 110, the end surface portion 112 and the innercylinder portion 111 are integrally provided with each other by bendinga metal plate. The stay portion 113 is bonded to the skirt portion 110.

The mouthpiece 41 is made of metal and has a higher strength than thecylindrical filling portion 40. Accordingly, at the time of filling oilin a filling station or the like, the cylindrical filling portion 40 canbe protected from a fuel filling nozzle inserted into the filler opening31.

On an inner peripheral portion of the inner cylinder portion 111, afemale threaded portion 111 a with which a threaded portion formed on anouter periphery of the tank cap 32 (FIG. 1) is threadedly engaged isprovided. The inner cylinder portion 111 is provided over substantiallythe whole length of the inner peripheral surface 93 a of the mouthpiecemounting cylinder portion 93.

The end surface portion 112 extends outward from an upper edge of theinner cylinder portion 111 in the radial direction. The end surfaceportion 112 is formed into a ring shape coaxially with the cylindricalfilling portion 40 as viewed in an axial direction of the mouthpiece 41.

The end surface portion 112 covers the distal end surface 93 b of themouthpiece mounting cylinder portion 93 from above. A gap is providedbetween the end surface portion 112 and the distal end surface 93 b.

The skirt portion 110 bends downward from the outer peripheral portionof the distal end surface 93 b, and extends downward parallel to theinner cylinder portion 111.

The skirt portion 110 includes: a fitting portion 115 which is fitted onthe upper portion 96 of the outer peripheral surface 93 c; and a largediameter portion 116 which covers a portion of the proximal end portion95 of the outer peripheral surface 93 c.

An inner peripheral surface of the fitting portion 115 is brought intoclose contact with the outer peripheral surface 93 c of the upperportion 96. In a seal groove 96 a formed on the upper portion 96, a sealmember 92 is disposed. The seal member 92 is deformed by beingcompressed between the seal groove 96 a and the fitting portion 115 thusproviding sealing between the upper portion 96 and the skirt portion110.

The large diameter portion 116 of the skirt portion 110 extends downwardfrom the fitting portion 115 to an area in the vicinity of the uppersurface of the upper half body 45. The large diameter portion 116 isformed to have the larger outer diameter and the larger inner diameterthan those of the fitting portion 115.

The large diameter portion 116 is formed with the diameter larger thanthe diameter of the fitting portion 115 such that the large diameterportion 116 is spaced apart from the outer peripheral surface 93 c ofthe mouthpiece mounting cylinder portion 93.

To be more specific, the large diameter portion 116 includes: a parallelportion 117 disposed parallel to the fitting portion 115; and anenlarged diameter portion 118 whose diameter is gradually increased fromthe fitting portion 115 to the parallel portion 117.

The parallel portion 117 is disposed parallel to the proximal endportion 95 of the mouthpiece mounting cylinder portion 93, and coversthe proximal end portion 95 from the outside. A gap S1 is formed betweenthe parallel portion 117 and the proximal end portion 95 in a radialdirection.

With reference to FIG. 2 and FIG. 13, the stay portion 113 of themouthpiece 41 includes: a plurality of mounting portions 119 whichextend radially outward from the outer peripheral portion of the largediameter portion 116 toward the respective mouthpiece fixing portions91; and a connecting portion 120 which connects the mounting portions119, 119 disposed adjacently to each other in the circumferentialdirection.

In the mounting portion 119, a fixing hole 121 through which themouthpiece fixing jig 42 passes is provided. To be more specific, thecollar 102 of the mouthpiece fixing jig 42 is made to pass through thefixing hole 121.

The fixing hole 121 is formed to have a diameter larger than an outerdiameter of the collar 102 so as to allow the movement of the mouthpiece41 by a predetermined distance with respect to the mouthpiece fixing jig42. An adjusting gap S2 is formed between the inner periphery of thefixing hole 121 and the outer periphery of the collar 102.

The stay portion 113 has a peripheral rib 122 (rib) which is raised froma periphery of the stay portion 113. The peripheral rib 122 is providedover the whole circumference of the stay portion 113 along the mountingportions 119 and the connecting portion 120.

One example of steps of assembling the mouthpiece 41 to the fuel tankbody 35 is described.

As shown in FIG. 13, the mouthpiece 41 is mounted on the mouthpiecemounting cylinder portion 93 by being inserted into the mouthpiecemounting cylinder portion 93 in the axial direction of the mouthpiecemounting cylinder portion 93 such that the mouthpiece mounting cylinderportion 93 is sandwiched between the skirt portion 110 and the innercylinder portion 111.

The respective mounting portions 119 of the stay portion 113 are broughtinto contact with the upper surfaces of the respective mouthpiece fixingportions 91 and hence, the mouthpiece 41 is positioned in the axialdirection of the mouthpiece mounting cylinder portion 93.

The collar 102 is made to pass through the fixing hole 121 of the stayportion 113 from above, and is set in the hole portion 100 of themouthpiece fixing portion 91. A lower end of the collar 102 is broughtinto contact with an upper surface of the nut 99.

When the mouthpiece fixing bolt 101 is fastened to the nut 99, aperipheral portion of the stay portion 113 around the fixing hole 121 isclamped between the flange portion 102 b of the collar 102 and the uppersurface of the mouthpiece fixing portion 91. With such a configuration,the mouthpiece 41 is fastened to the mouthpiece fixing portions 91 ofthe fuel tank body 35 by the mouthpiece fixing bolts 101.

In the first embodiment, the mouthpiece 41 is fastened by the mouthpiecefixing bolts 101 in a state where the mouthpiece 41 is inserted into themouthpiece mounting cylinder portion 93 thus being fixed to the fueltank body 35. Accordingly, in removing the mouthpiece 41 at the time ofmaintenance the like, the mouthpiece 41 can be easily removed from themouthpiece mounting cylinder portion 93 by removing the mouthpiecefixing bolt 101 and by pulling out the mouthpiece 41. The mouthpiece 41is not swaged to the mouthpiece mounting cylinder portion 93 and hence,the removed mouthpiece 41 can be mounted on the mouthpiece mountingcylinder portion 93 in a recycling manner.

FIG. 16 is a cross-sectional view showing a mounting state of themouthpiece 41 when there is an error in size.

In the mouthpiece mounting cylinder portion 93, a dimensional tolerancein manufacture is set. FIG. 16 shows a case where an outer diameter ofthe upper portion 96 of the mouthpiece mounting cylinder portion 93 is aminimum value of the dimensional tolerance, and an inner diameter of themouthpiece mounting cylinder portion 93 is a maximum value of thedimensional tolerance as an example.

As shown in FIG. 16, when an actual size of the mouthpiece mountingcylinder portion 93 is deviated from a median of the tolerance, there isa possibility that the mouthpiece 41 is assembled to the mouthpiecemounting cylinder portion 93 in a state where an axis 41 a is displacedfrom an axis C which passes the center of the mouthpiece mountingcylinder portion 93 in a radial direction of the mouthpiece mountingcylinder portion 93.

In this embodiment, the adjusting gap S2 (FIG. 13) is provided betweenthe inner periphery of the fixing hole 121 of the mouthpiece 41 and theouter periphery of the collar 102 of the mouthpiece fixing jigs 42 and,at the same time, the gap S1 (FIG. 13) is provided between the largediameter portion 116 and the proximal end portion 95 in the radialdirection. In this embodiment, the adjusting gap S2 and the gap S1 havesubstantially the same size.

With such a configuration, the mouthpiece 41 can move in the radialdirection of the mouthpiece mounting cylinder portion 93 by an amountcorresponding to the adjusting gap S2 and an amount of the gap S1, andthe mouthpiece 41 can be fixed by the mouthpiece fixing bolt 101 in sucha state. Accordingly, the mouthpiece 41 can be mounted on the mouthpiecemounting cylinder portion 93 while allowing the dimensional tolerance inthe manufacture of the mouthpiece mounting cylinder portion 93.

In this embodiment, the gap S1 is set such that even when the mouthpiece41 is moved by making use of the adjusting gap S2, the gap S1 does notbecome zero. That is, the gap S1 is always formed between the largediameter portion 116 and the cylindrical filling portion 40.

As has been described heretofore, according to the first embodiment towhich the present invention is applied, the resin-made fuel tank 30includes the resin-made fuel tank body 35 provided by bonding the upperhalf body 45 and the lower half body 46 to each other, and the barriersheet layer 36 provided on the inner surface of the fuel tank body 35and provided for reducing permeation of fuel from the fuel tank body 35,the edge of the barrier sheet layer 36 is disposed in the vicinity ofthe upper bonding surface 47 c and the lower bonding surface 48 c whichare bonded to each other in a state where the upper half body 45 and thelower half body 46 are mated to each other, the edge of the barriersheet layer 36 has the bent portions 61, 62 which bend toward theoutside of the fuel tank body 35, the bent portions 61, 62 are embeddedin the fuel tank body 35 at positions away from the upper bondingsurface 47 c and the lower bonding surface 48 c.

With such a configuration, the bent portions 61, 62 which bend towardthe outside of the fuel tank body 35 are embedded in the fuel tank body35 and hence, the edge of the barrier sheet layer 36 is strongly fixedto the fuel tank body 35. Accordingly, the barrier sheet layer 36 isminimally influenced at the time of bonding the upper bonding surface 47c and the lower bonding surface 48 c to each other. Further, the bentportions 61, 62 are disposed at positions spaced apart from the upperbonding surface 47 c and the lower bonding surface 48 c respectively andhence, the bent portions 61, 62 are not bonded to each other at theupper bonding surface 47 c and the lower bonding surface 48 c. With sucha configuration, it is unnecessary to control the bonding of the barriersheet layer 36 at the time of bonding the upper bonding surface 47 c andthe lower bonding surface 48 c to each other and hence, the resin-madefuel tank 30 can be easily manufactured.

The bent portions 61, 62 of the barrier sheet layer 36 extend toward theoutside of the fuel tank body 35 parallel to the upper bonding surface47 c and the lower bonding surface 48 c respectively. With such aconfiguration, surfaces of the bent portions 61, 62 are disposedperpendicular to the bonding direction between the upper bonding surface47 c and the lower bonding surface 48 c and hence, the surfaces of thebent portions 61, 62 can efficiently receive a force generated at thetime of bonding the upper half body 45 and the lower half body 46 toeach other.

Further, the width W1 of the upper bonding portion 47 which has theupper bonding surface 47 c at the end surface thereof is larger than thethickness t1 of the side wall portion 45 a of the fuel tank body 35, andthe width W2 of the lower bonding portion 48 which has the lower bondingsurface 48 c at the end surface thereof is larger than the thickness t2of the side wall portion 46 a of the fuel tank body 35. With such aconfiguration, an area of the upper bonding surface 47 c and an area ofthe lower bonding surface 48 c can be widely ensured and hence, thebonding strength between the upper bonding surface 47 c and the lowerbonding surface 48 c can be increased.

Further, the upper bonding portion 47 and the lower bonding portion 48are formed in a flange shape protruding toward the outside of the fueltank body 35, and the upper bonding portion 47 and the lower bondingportion 48 have the pressing surfaces 47 d, 48 d to be pressed inapplying pressure-bonding to the upper bonding portion 47 and the lowerbonding portion 48 respectively, and the pressing surfaces 47 d, 48 doverlap with the upper bonding surface 47 c and the lower bondingsurface 48 c respectively in the pressing direction P. With such aconfiguration, at portions where the pressing surfaces 47 d, 48 doverlap with the upper bonding surface 47 c and the lower bondingsurface 48 c respectively in the pressing direction P, a pressing forceof the pressing surfaces 47 d, 48 d can be directly transmitted to theupper bonding surface 47 c and the lower bonding surface 48 crespectively. Accordingly, the upper bonding surface 47 c and the lowerbonding surface 48 c can be strongly bonded to each other.

Further, the barrier sheet layer 36 includes the upper barrier sheetlayer 36 a mounted on the upper half body 45 which forms one split body,and the lower barrier sheet layer 36 b which is provided on the lowerhalf body 46 which forms the other split body. The bent portion 61 ofthe upper barrier sheet layer 36 a and the bent portion 62 of the lowerbarrier sheet layer 36 b are embedded on the fuel tank body 35 in aspaced apart manner. With such a configuration, the bent portion 61 andthe bent portion 62 are not bonded to each other at the upper bondingsurface 47 c and the lower bonding surface 48 c. Accordingly, it isunnecessary to control the bonding of the barrier sheet layer 36 at thetime of bonding the upper bonding surface 47 c and the lower bondingsurface 48 c to each other and hence, the fuel tank 30 can be easilymanufactured.

The barrier sheet layer 36 is formed by adhering the outer layers 57 a,57 b which are formed of a layer made of high density polyethylene toboth surfaces of the barrier layer 55 which is a layer made of ethylenevinyl alcohol copolymer with the adhesive layers 56, 56 interposedtherebetween respectively. The barrier sheet layer 36 is bonded to theinner surface of the fuel tank body 35 made of high density polyethylenewith the outer layer 57 a interposed therebetween. With such aconfiguration, the barrier sheet layer 36 is formed such that the outerlayer 57 a which is a layer made of high density polyethylene is bondedto the inner surface of the fuel tank body 35 made of the same materialas the outer layer 57 a, that is, high density polyethylene.Accordingly, the barrier sheet layer 36 can be strongly bonded to theinner surface of the fuel tank body 35.

Further, cut surfaces 61 a, 62 a trimmed in the thickness direction areformed on distal ends of the bent portions 61, 62 by a cutting blade.Accordingly, dimensional accuracy of the bent portions 61, 62 can beenhanced so that the bent portions 61, 62 can be properly embedded inthe fuel tank body 35.

The upper bonding surface 47 c and the lower bonding surface 48 crespectively include: the planar surface portion 47 a, 48 a disposedperpendicular to the pressure bonding direction (pressing direction P)of the upper bonding surface 47 c and the lower bonding surface 48 c;and the inclined surface portion 47 b, 48 b inclined with respect to theplanar surface portion 47 a, 48 a. The upper bonding portion 47 havingthe upper bonding surface 47 c on the end surface thereof and the lowerbonding portion 48 which has the lower bonding surface 48 c at the endsurface thereof are formed in a flange shape protruding toward theoutside of the fuel tank body 35, and the upper bonding portion 47 andthe lower bonding portion 48 respectively include the pressing surface47 d, 48 d to be pressed in applying pressure-bonding to the upperbonding surface 47 c and the lower bonding surface 48 c, and the widthW3 of the upper bonding portion 47 and the lower bonding portion 48 atthe inclined surface portions 47 b, 48 b is smaller than the widths W1,W2 of the upper bonding portion 47 and the lower bonding portion 48 atthe planar surface portions 47 a, 48 a.

With such a configuration, at the time of pressure bonding, the inclinedsurface portions 47 b, 48 b receive a pressure bonding force smallerthan a pressure bonding force which the planar surface portions 47 a, 48a perpendicular to the pressure bonding direction (pressing direction P)receive. However, the width W3 of the inclined surface portions 47 b, 48b is smaller than the widths W1, W2 of the planar surface portions 47 a,48 a and hence, it is possible to acquire a sufficient surface pressureon the inclined surface portions 47 b, 48 b. Accordingly, the wholeupper bonding surface 47 c and the whole lower bonding surface 48 c canbe favorably bonded to each other.

According to the first embodiment to which the present invention isapplied, the resin-made fuel tank 30 includes: the resin-made fuel tankbody 35 provided by bonding the upper half body 45 and the lower halfbody 46 to each other; the barrier sheet layer 36 provided on the innersurface of the fuel tank body 35 and provided for reducing permeation offuel from the fuel tank body 35; and the front mounting stay 37 and therear mounting stays 38L, 38R provided for mounting the fuel tank body 35on the vehicle body. The front mounting stay 37 and the rear mountingstays 38L, 38R are provided on the fuel tank body 35 at positionsvertically separated from the upper bonding surface 47 c and the lowerbonding surface 48 c which are bonded to each other in a state where theupper half body 45 and the lower half body 46 are mated to each other.

With such a configuration, the front mounting stay 37 and the rearmounting stays 38L, 38R are provided on the fuel tank body 35 atpositions vertically away from the upper bonding surface 47 c of theupper half body 45 and the lower bonding surface 48 c of the lower halfbody 46 and hence, it is possible to prevent the barrier sheet layer 36in the vicinity of the upper bonding surface 47 c and the lower bondingsurface 48 c from being influenced by an externa force from the frontmounting stay 37 and the rear mounting stays 38L, 38R. Accordingly, itis possible to effectively protect the barrier sheet layer 36 against anexternal force.

The front mounting stay 37 and the rear mounting stay 38L, 38R arespaced apart from each other in the vertical direction and in thelongitudinal direction. With such a configuration, an external forcewhich acts on the fuel tank body 35 from the plurality of front mountingstay 37 and rear mounting stays 38L, 38R can be dispersed to a wideregion of the fuel tank body 35. Accordingly, it is possible toeffectively protect the barrier sheet layer 36 against an externalforce.

The front mounting stay 37 and the rear mounting stays 38L, 38R areprovided to the upper half body 45 and the lower half body 46 in a splitmanner. With such a configuration, an external force which acts on thefuel tank body 35 from the front mounting stay 37 and the rear mountingstays 38L, 38R is dispersed to the upper half body 45 and the lower halfbody 46. Accordingly, the barrier sheet layer 36 can be effectivelyprotected against an external force.

The mounting stay includes the front mounting stay 37 which is providedon the front portion of the fuel tank body 35 and the rear mountingstays 38L, 38R which are provided on the rear portion of the fuel tankbody 35, and the front mounting stay 37 is disposed at the centerportion of the upper half body 45 in the lateral direction, and the rearmounting stays 38L, 38R are disposed on the lower half body 46 in a leftand right pair. With such a configuration, an external force isdispersed in the longitudinal direction from the front mounting stay 37mounted on the front portion of the fuel tank body 35 and the rearmounting stays 38L, 38R mounted on the rear portion of the fuel tankbody 35 and, at the same time, is dispersed to the upper half body 45and the lower half body 46 thus acting on the upper bonding surface 47 cand the lower bonding surface 48 c. Accordingly, it is possible toeffectively protect the barrier sheet layer 36. Further, the fuel tankbody 35 is supported at three points, that is, at the front mountingstay 37 and the rear mounting stays 38L, 38R and hence, the fuel tankbody 35 can be effectively and strongly mounted on the vehicle bodyframe F with the minimum configuration.

The front mounting stay 37 has the mounting hole 72 through which thetank fixing jig 39 a fixed to the vehicle body frame F passes, and thefront mounting stay 37 has the upper surface groove 71 a and the lowersurface groove 71 b as the fragile portions in the vicinity of themounting hole 72. The rear mounting stays 38L, 38R respectively have themounting hole 82 through which the tank fixing jig 39 b fixed to thevehicle body frame F passes, and the rear mounting stays 38L, 38Rrespectively have the grooves 83 b, 83 b which form the fragile portionsin the vicinity of the mounting hole 82 respectively. With such aconfiguration, when an excessive external force acts on the frontmounting stay 37 and the rear mounting stays 38L, 38R, the upper surfacegroove 71 a and the lower surface groove 71 b of the front mounting stay37 and the grooves 83 b, 83 b of the left and right rear mounting stays38L, 38R disposed at positions away from the upper bonding surface 47 cand the lower bonding surface 48 c are broken prior to the upper bondingsurface 47 c and the lower bonding surface 48 c. Accordingly, it ispossible to protect the barrier sheet layer 36 in the fuel tank body 35.

The fragile portions are formed of the upper surface groove 71 a, thelower surface groove 71 b, and the grooves 83 b, 83 b which are providedon the peripheries of the mounting holes 72, 82. With such aconfiguration, the fragile portions can be provided in a compact mannerat positions remote from the upper bonding surface 47 c and the lowerbonding surface 48 c. Accordingly, an external force which acts on theupper bonding surface 47 c and the lower bonding surface 48 c from thefront mounting stay 37 and the left and right rear mounting stays 38L,38R is reduced thus protecting the barrier sheet layer 36.

The upper bonding surface 47 c is provided on the upper bonding portion47 which is the flange portion extending toward the outside of the fueltank body 35, and the front mounting stay 37 includes the reinforcingrib 74 which extends from the upper bonding portion 47. With such aconfiguration, strength and rigidity of the front mounting stay 37 canbe increased by the upper bonding portion 47 and the reinforcing rib 74.Accordingly, the fuel tank body 35 can be strongly supported by thefront mounting stay 37.

The lower bonding surface 48 c is provided on the lower bonding portion48 which is the flange portion extending toward the outside of the fueltank body 35, and the rear mounting stays 38L, 38R respectively includethe reinforcing ribs 83, 83 extending from the lower bonding portion 48.With such a configuration, strength and rigidity of the rear mountingstays 38L, 38R can be increased by the lower bonding portion 48 and thereinforcing ribs 83, 83. Accordingly, the fuel tank body 35 can bestrongly supported by the rear mounting stays 38L, 38R.

According to the first embodiment to which the present invention isapplied, the resin-made fuel tank 30 includes: the resin-made fuel tankbody 35; the resin-made cylindrical filling portion 40 for filling aliquid, the cylindrical filling portion 40 provided on the fuel tankbody 35; and the mouthpiece 41 engageable with the cylindrical fillingportion 40, and capable of covering the inner peripheral surface 93 a,the distal end surface 93 b and the outer peripheral surface 93 c of thecylindrical filling portion 40, wherein the fuel tank body 35 has themouthpiece fixing portion 91 to which the mouthpiece fixing jig 42 forfixing the mouthpiece 41 to the fuel tank body 35 is fixed. Themouthpiece 41 has the annular skirt portion 110 which covers the outerperipheral surface 93 c, the skirt portion 110 has the fitting portion115 which is fitted on the upper portion 96 of the outer peripheralsurface 93 c on the upper portion thereof, and has the large diameterportion 116 having the diameter larger than the fitting portion 115 onthe lower portion thereof, the mouthpiece 41 has the stay portion 113extending from the large diameter portion 116 toward the outside of themouthpiece 41 in the radial direction, and the fixing hole 121 throughwhich the mouthpiece fixing jig 42 passes is provided in the stayportion 113.

With such a configuration, the mouthpiece 41 engageable with thecylindrical filling portion 40 is fixed to the mouthpiece fixing portion91 of the fuel tank body 35 by the mouthpiece fixing jig 42 which passesthrough the fixing hole 121 formed in the stay portion 113 extendingfrom the large diameter portion 116. Accordingly, the mouthpiece 41 canbe easily mounted on or removed from the cylindrical filling portion 40by mounting or removing the mouthpiece fixing jig 42. Further, themouthpiece 41 has the large diameter portion 116 having the diameterlarger than the diameter of the fitting portion 115 and hence, themouthpiece 41 can be integrally moved with the stay portion 113 by anamount corresponding to the gap S1 formed between the large diameterportion 116 and the outer peripheral surface 93 c of the cylindricalfilling portion 40. Accordingly, even in the case where an error in sizeoccurs in the manufacture of the cylindrical filling portion 40, theerror can be absorbed by the movement of the mouthpiece 41. In thismanner, the mouthpiece 41 can be mounted or removed while allowing anerror in size in the manufacture of the cylindrical filling portion 40.

The fixing hole 121 has a diameter larger than a diameter of themouthpiece fixing jig 42 so as to allow the movement of the mouthpiece41 with respect to the cylindrical filling portion 40 by a predetermineddistance in the radial direction of the cylindrical filling portion 40.With such a configuration, the mouthpiece 41 can be moved in the radialdirection of the cylindrical filling portion 40 by an amount that thefixing hole 121 is movable with respect to the mouthpiece fixing jig 42.Accordingly, the mouthpiece 41 can be mounted or removed while allowingan error in size in the manufacture of the cylindrical filling portion40.

The barrier sheet layer 36 provided for lowering permeation of a fuelstored in the fuel tank body 35 is provided on the inner surface of thefuel tank body 35, and the mouthpiece fixing portion 91 is the nut 99embedded in the surface of the fuel tank body 35, and the mouthpiecefixing jig 42 is the mouthpiece fixing bolt 101 threadedly engageablewith the nut 99, the nut 99 is embedded in the inner protruding portion98 which projects toward the inside of the fuel tank body 35, and thedistal end surface 98 a of the inner protruding portion 98 has asemispherical convex shape. With such a configuration, the distal endsurface 98 a of the inner protruding portion 98 has a semisphericalconvex shape and hence, it is possible to prevent the concentration of astress on the barrier sheet layer 36 provided on the distal end surface98 a of the inner protruding portion 98 and thereby a degree of freedomin arrangement of the mouthpiece fixing portion 91 can be enhanced.

A plurality of the mouthpiece fixing portions 91 may be disposedconcentrically around the cylindrical filling portion 40 at asubstantially equal interval. With such a configuration, an externalforce which acts on the mouthpiece fixing portion 91 can be effectivelydispersed and hence, the concentration of a stress around thecylindrical filling portion 40 can be reduced.

The mouthpiece 41 has the peripheral rib 122 raised from the peripheryof the stay portion 113, and the rib 122 is formed continuously betweena plurality of the fixing holes 121 disposed on the periphery of theskirt portion 110. With such a configuration, strength and rigidity ofthe mouthpiece 41 can be enhanced and hence, the cylindrical fillingportion 40 can be effectively protected by the mouthpiece 41.

The large diameter portion 116 has: the parallel portion 117 disposedparallel to the fitting portion 115; and the enlarged diameter portion118 whose diameter is gradually increased from the fitting portion 115to the parallel portion 117. With such a configuration, the gap S1formed between the parallel portion 117 and the outer peripheral surface93 c of the cylindrical filling portion 40 can be easily controlled.Further, rigidity of the skirt portion 110 can be enhanced by theenlarged diameter portion 118 and hence, the cylindrical filling portion40 can be effectively protected by the mouthpiece 41.

The cylindrical filling portion 40 has the finished portion 90 finishedby machining on a portion thereof (the upper portion 96) on which thefitting portion 115 of the mouthpiece 41 is fitted. With such aconfiguration, the portion of the cylindrical filling portion 40 onwhich the fitting portion 115 of the mouthpiece 41 is fitted can beworked with high accuracy by machining. An error in size which occurs inmachining can be absorbed by the movement of the mouthpiece 41.

The cylindrical filling portion 40 has the proximal end portion 95 whichis covered by the large diameter portion 116 of the mouthpiece 41, andthe outer diameter of the proximal end portion 95 is larger than theouter diameter of the portion (upper portion 96) of the cylindricalfilling portion 40 which is covered by the fitting portion 115. Withsuch a configuration, the proximal end portion 95 of the cylindricalfilling portion 40 can have a large diameter corresponding to the largediameter portion 116 of the mouthpiece 41 and hence, strength andrigidity of the cylindrical filling portion 40 can be enhanced.

The seal member 92 is interposed between the fitting portion 115 of themouthpiece 41 and the outer peripheral surface 93 c of the cylindricalfilling portion 40. With such a configuration, in the case where anerror in size is absorbed by the movement of the mouthpiece 41, hermeticproperty between the fitting portion 115 and the outer peripheralsurface 93 c of the cylindrical filling portion 40 can be ensuredbecause of deflection of the seal member 92.

Second Embodiment

Hereinafter, a second embodiment to which the present invention isapplied is described with reference to FIG. 17 and FIG. 18. In thissecond embodiment, parts having substantially the same configuration asthe above-mentioned first embodiment are given the same symbols andtheir description is omitted.

The second embodiment differs from the above-mentioned first embodimentin respect of the configuration of a mounting stay in conformity with avehicle body frame F2.

FIG. 17 is a perspective view of a mounting structure of a fuel tank 230according to a second embodiment as viewed from a left upper side. FIG.18 is a schematic view of the mounting structure of the fuel tank 230 asviewed from a front side.

A motorcycle 201 includes the vehicle body frame F2, and a fuel tank230. Although other parts of the motorcycle 201 are not shown in FIG.17, the motorcycle 201 has substantially the same configuration as themotorcycle 1.

The vehicle body frame F2 includes a head pipe portion 14, one mainframe 215 which extends rearward in a rearward and downward directionfrom the head pipe portion 14, a down frame 16, and a seat frame 217which extends rearward from the main frame 215.

The main frame 215 has tank support portions 215 a, 215 a which protrudeleftward and rightward respectively on side surfaces thereof.

The fuel tank 230 includes a fuel tank body 235, and a barrier sheetlayer 36 (see FIG. 3).

The fuel tank body 235 is arranged so as to straddle the main frame 215from above in the lateral direction, and is supported on the main frame215.

The fuel tank body 235 includes: an upper portion 235 a arranged abovethe main frame 215; and a pair of left and right side portions 235 b,235 b which extends downward after passing along left and right sides ofthe main frame 215 from the upper portion 235 a.

The fuel tank body 235 is formed into a tank shape by bonding an upperhalf body 245 and a lower half body 246 to each other at bondingsurfaces 247 c, 248 c.

In the upper half body 245, on inner side surfaces of the side portions235 b, 235 b, front mounting stays 237, 237 (mounting stay) in whichtank support portions 215 a, 215 a are fitted are provided. A frontportion of the fuel tank body 235 is mounted on the tank supportportions 215 a, 215 a.

The front mounting stays 237, 237 are spaced apart from the bondingsurfaces 247 c, 248 c in the upward direction.

Accordingly, it is possible to prevent the barrier sheet layer 36 in thevicinity of the bonding surfaces 247 c, 248 c from being influenced byan external force from the front mounting stays 237, 237. Accordingly,it is possible to protect the barrier sheet layer 36 against an externalforce.

The upper half body 245 includes a rear mounting stay 238 extendingrearward from a rear end portion thereof. A rear portion of the fueltank body 235 is fixed to the vehicle body frame F2 by a tank fixing jig239 which is made to pass through the rear mounting stay 238 from above.

The above-mentioned embodiments show one mode to which the presentinvention is applied, and the present invention is not limited to theabove-mentioned embodiments.

In the above-mentioned embodiments, the description has been made bytaking the upper half body 45 and the lower half body 46 as the exampleof the split bodies which form the fuel tank body 35. However, thepresent invention is not limited to the above-mentioned configuration,and the fuel tank body 35 may be split into three or more split bodies.For example, a fuel tank body may be formed by bonding the lower halfbody 46 to an upper half body which is formed of two split bodies.

In the above-mentioned embodiments, the description has been made bytaking the motorcycle 1 as an example of a saddle riding vehicle.However, the present invention is not limited to the motorcycle 1, andthe resin-made fuel tank according to the present invention is alsoapplicable to various saddle riding vehicles such as a three-wheeledsaddle riding vehicle provided with two front wheels or two rear wheelsand a saddle riding vehicle provided with four or more wheels. Further,the present invention may be also applicable to a resin-made fuel tankother than the vehicle-use resin-made fuel tank.

REFERENCE SIGNS LIST

-   -   30: fuel tank (resin-made fuel tank)    -   35: fuel tank body    -   36: barrier sheet layer    -   36 a: upper barrier sheet layer (one barrier sheet layer)    -   36 b: lower barrier sheet layer (the other barrier sheet layer)    -   45: upper half body (split body, one split body)    -   45 a: side wall portion (wall portion)    -   46: lower half body (split body, the other split body)    -   46 a: side wall portion (wall portion)    -   47: upper bonding portion (bonding portion)    -   47 a, 48 a: planar surface portion    -   47 b, 48 b: inclined surface portion    -   47 c: upper bonding surface (bonding surface)    -   47 d, 48 d: pressing surface    -   48: lower bonding portion (bonding portion)    -   48 c: lower bonding surface (bonding surface)    -   55: barrier layer (layer made of ethylene vinyl alcohol        copolymer)    -   56, 56: adhesive layer    -   57 a, 57 b: outer layer (layer made of high density        polyethylene)    -   61: bent portion (bent portion of one barrier sheet layer)    -   61 a, 62 a: cut surface    -   62: bent portion (bent portion of the other barrier sheet layer)    -   P: pressing direction    -   W1: width (width of bonding portion)    -   W2: width (width of bonding portion)    -   t1: thickness (thickness of wall portion)    -   t2: thickness (thickness of wall portion)

The invention claimed is:
 1. A resin-made fuel tank comprising: aresin-made fuel tank body comprising split bodies; and a barrier sheetlayer provided on an inner surface of the fuel tank body and providedfor reducing permeation of fuel from the fuel tank body, wherein thesplit bodies comprise a first half body that is one split body and asecond half body that is an other split body, wherein the barrier sheetlayer comprises a first barrier sheet layer that is provided on thefirst half body and a second barrier sheet layer that is provided on thesecond half body, the first half body includes a first bonding surfaceof a first bonding portion that is formed at a peripheral portion of thefirst half body and the second half body includes a second bondingsurface of a second bonding portion that is formed at a peripheralportion of the second half body, the first bonding surface is a surfacefacing the second half body and the second bonding surface is a surfacefacing the first half body, the first bonding surface and the secondbonding surface are mated to each other, wherein an edge of the firstbarrier sheet layer is disposed in a vicinity of the first bondingsurface, a first bent portion which bends toward an outside of the fueltank body is provided at the edge of the first barrier sheet layer,wherein an edge of the second barrier sheet layer is disposed in avicinity of the second bonding surface, a second bent portion whichbends toward the outside of the fuel tank body is provided at the edgeof the second barrier sheet layer, the first bent portion is positionedin the first half body at a position spaced apart from the first bondingsurface, the second bent portion is positioned in the second half bodyat a position spaced apart from the second bonding surface, and thefirst bent portion and the second bent portion are spaced apart fromeach other, a protruding portion that is resin is formed at a bondingportion of the first bonding surface and the second bonding surface, andthe first bent portion and the second bent portion are spaced apart fromthe protruding portion in an upward direction and in a downwarddirection, respectively.
 2. The resin-made fuel tank according to claim1, wherein the first bent portion and the second bent portion extendtoward the outside of the fuel tank body parallel to the first bondingsurface and the second bonding surface.
 3. The resin-made fuel tankaccording to claim 1, wherein widths of the first bonding portion andthe second bonding portion are larger than a thickness of a wall portionof the fuel tank body.
 4. The resin-made fuel tank according to claim 3,wherein the first bonding portion and the second bonding portion areformed in a flange shape protruding toward the outside of the fuel tankbody, and each of the first and second bonding portions has a pressingsurface at a distal end of the peripheral portions, each pressingsurface opposes and faces away from its respective bonding surface, andat least a part of the pressing surfaces overlap with the bondingsurfaces.
 5. The resin-made fuel tank according to claim 1, wherein thefirst barrier sheet layer and the second barrier sheet layer include ahigh density polyethylene layer and an ethylene vinyl alcohol copolymerlayer, the high density polyethylene layer is provided at both surfacesof the ethylene vinyl alcohol copolymer layer with an adhesive layerinterposed between the high density polyethylene layer and the ethylenevinyl alcohol copolymer layer, and the first barrier sheet layer and thesecond barrier sheet layer are bonded to the inner surface of the fueltank body made of high density polyethylene with a high densitypolyethylene layer interposed therebetween.
 6. The resin-made fuel tankaccording to claim 1, wherein a cut surface that is trimmed in athickness direction of the first barrier sheet layer and the secondbarrier sheet layer is formed on a periphery of the first barrier sheetlayer and the second barrier sheet layer by a cutting blade, the cutsurface is formed at a distal end of the first bent portion and thesecond bent portion.
 7. The resin-made fuel tank according to claim 1,wherein the first and second bonding surfaces include: a planar surfaceportion that is parallel to the first bonding surface and the secondbonding surface; and an inclined surface portion inclined with respectto the planar surface portion, the first bonding portion and the secondbonding portion having the first bonding surface and the second bondingsurface on an end surface is formed in a flange shape protruding towardthe outside of the fuel tank body, each of the first and second bondingportions include a pressing surface at a distal end of the peripheralportions, each pressing surface opposes and faces away from itsrespective bonding surface, and widths of the first bonding portion andthe second bonding portion are smaller at the inclined surface portionthan at the planar surface portion.